Added isort to setup, makefile and tox

.isort.cfg

@@ -0,0 +1,15 @@
+[settings]
+profile=black
+force_grid_wrap=1
+multi_line_output=3
+honor_noqa=true
+float_to_top=true
+combine_as_imports=true
+force_sort_within_sections=true
+include_trailing_comma=true
+extra_standard_library=pytest
+known_first_party=eth
+line_length=88
+use_parentheses=true
+# skip `__init__.py` files because sometimes order of initialization is important
+skip=__init__.py